This invention relates generally to power management, and more particularly to controlling malfunctions with power management.
The power consumption of electronic devices is important. The more power that an electronic device uses corresponds to a number of problems such as increased energy costs and increased heat. Furthermore, many devices utilize battery backups in case of power outages. If devices use too much power, these battery backups are of little value. Also, energy conservation saves money and conserves natural resources.
Electronic devices are often designed to reduce the power consumption. For example, operating voltages of some computer systems have moved from five volts to three volts in order to reduce power. However, power reduction of electronic devices can only be reduced so far by designing.
One way electronic devices can reduce power is by utilizing a power management environment. By utilizing a power management environment, electronic devices and systems may be placed into an energy conserving xe2x80x9csleepxe2x80x9d state. In this sleep state, parts or components of the system may shut down or operate at a low capacity. This permits energy saving by powering down these devices while they are not being used. The sleep state is different than simply shutting down a device. An electronic device may xe2x80x9cwake upxe2x80x9d from a sleep state and continue operation as before the device entered the sleep state.
Power management environments are often used in customer premise equipment (CPE) such as personal computers, workstations, network computers, and other electronic equipment. Personal computers can enter a xe2x80x9csleepxe2x80x9d state after some amount of time of inactivity. In this sleep state, devices such as monitors, hard drives, modems, video cards and tape drives may shut down thus conserving energy. The processor may shut down or operate at a fraction of normal speed also conserving energy. Personal computers can xe2x80x9cwake upxe2x80x9d from this sleep state by events such as mouse movement, keyboard being used and a network message.
Electronic devices often interact with each other. Naturally, it is hoped that errors do not occur but if errors or malfunctions do occur, something needs to be done to prevent further errors. Many of today""s electronic devices implement a xe2x80x9cwatchdog timerxe2x80x9d function to control and prevent proliferation of errors. This function assures that if a device""s software or another device controlling it malfunction, steps are taken to either return the device back to an operating state (i.e., reset it) or disable it from behaving in an undesired manner until the problem is corrected. Devices utilizing a watchdog timer expect to receive some type of signal from another device at a regular interval. This xe2x80x9csignalxe2x80x9d resets the watchdog timer. If the watchdog timer is not reset, the device utilizing the watchdog timer can assume that an error has occurred and take appropriate steps.
When watchdog systems are used in conjunction with power management environments, additional problems can occur when devices enter a sleep state. When a device enters a sleep state, it is no longer able to communicate with another device and reset the watchdog timer in the watchdog system. Thus, devices may consider a device in a sleep state to be non-functioning. For example, consider a personal computer operating with a cable modem using a watchdog system in a power management environment. If the personal computer enters a sleep state it can no longer reset or clear the watchdog timer. The cable modem assumes that the personal computer is malfunctioning and disables its output. Then, when the computer exits the sleep state the computer has to reestablish its connection to the network which may involve resetting the cable modem. This can result in missing an incoming message.
One solution to this problem is to have a multiple device system and not use a watchdog timer. There is no longer concern over one device shutting down or disabling when another device enters a xe2x80x9csleepxe2x80x9d state. However, this too is undesirable because errors can then proliferate. For example, consider a personal computer operating with a cable modem in a power management environment without using a watchdog system. If the personal computer malfunctions and the error is not caught, the cable modem could corrupt other users"" information on the cable system.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a watchdog system in a power management environment.
One embodiment of the invention is a system comprising a first device and a second device. The first device operates in a power management environment and has a sleep status signal for indicating a sleep status to the second device. The second device is coupled to the first device and checks for malfunctions of the first device.
Another embodiment of the invention is a system comprising a plurality of customer premise equipment (CPE) devices, a plurality of cable modems, and a cable modem network. The plurality of CPE devices operate in a power management environment. The plurality of cable modems are coupled to the plurality of CPE devices and the cable modem network for providing network access to the plurality of CPE devices.
Other embodiments of systems and methods are disclosed.